This invention relates to a laminated wooden board product and method of constructing such a product. Laminated board products are increasingly used to construct furniture and as building components. Such products, referred to generically as "plywood" actually includes many types of products, including those manufactured from layers of fiberboard, chipboard, particleboard, high pressure plastic laminates, thin layers of wood veneer and the like. A typical plywood product may include several relatively thin layers of wood laminated together using a urea formaldehyde resin glue. The layers are bound together using heat and pressure to permanently cure the resin.
The typical manufacturing process comprises the formation of a urea formaldehyde resin glue by mixing with extenders and catalyst. The glue must be applied to the layers and be laminated together relatively quickly after mixing, while the glue is wet and before the resin begins to cure. Since the resin must be thermally cured, the amount of heat required to manufacture plywood is relatively great, resulting in a correspondingly large consumption of energy.
The process described above also inherently involves the use of large quantities of water and the creation of a certain amount of free formaldehyde in the glue and waste in the form of excess glue which is usually disposed of by flushing into a waste water disposal system, which may be a municipal sewage system. Environmental concerns are resulting in increasingly strict controls on disposal of such products and the concentration of free formaldehyde in the workplace.
The prior art recognizes the use of certain thermoplastic fibers as adhesives, based on the inherent characteristics of the fiber constituents, and that some such fibers will bond to wood. Most thermoplastic fibers melt at such high temperatures that their use on a large scale as an adhesive would require extravagant energy usage. However, insofar as is known, the prior art does not disclose the use of thermoplastic fibers to bond multiple layers of wood to each other to form laminated wooden board products.
The invention disclosed in this application according to its various embodiments uses low melt thermoplastic fibers as a substitute for water-based resin adhesives to produce an immediate type II water resistant bond.